INDIANAPOLIS — Alexander Rossi, a 24-year-old American rookie, stretched his fuel mileage to the absolute limit and won the Indianapolis 500 on Sunday, in the 100th edition of the storied race.
“I’m out of fuel, guys,” Rossi told his crew over the radio moments after taking the checkered flag at the chaotic finish. His Honda-powered IndyCar had to be topped up with fuel to make it to the celebration in victory circle.
The race’s runner-up, Carlos Munoz, 24, was leading with three laps to go and said he thought his car had enough fuel to win. But his crew ordered him to the pits, telling him he would otherwise come up half a lap short.
“One day, I will win this race,” said a dejected Munoz, who rebounded to be scored at 4.49 seconds behind Rossi.
Just behind him was Josef Newgarden, 26, who also had to make a late stop after running among the leaders for the whole race. “We had the car to win today,” he said. “But at the end, it didn’t fall our way.”
Tony Kanaan came in fourth, followed by Charlie Kimball.
“I have no idea how we pulled that off,” an emotional Rossi said as he sipped from a quart bottle of 2 percent milk, the traditional drink of Indy winners. “At one point, we were 33rd. But we just rolled the dice and went for it.”
Rossi, who had started 11th in the 33-car field, did indeed fall to last in the early going. But his team gambled on an out-of-sequence pit strategy. He saved fuel the whole race. He patiently worked his way back through the field and into the top 10. In outlasting speedier competitors, he completely crossed up the conventional wisdom that says that to win Indy, a driver needs to stay among the leaders and out of trouble all day.
Rossi, who turned to IndyCar racing this season after being snubbed for a seat at the new United States-based Haas Formula One team, had landed an 11th-hour ride in the series with the car owner Bryan Herta and Andretti Autosport.
“Bryan pulled off a tremendous strategy once again,” Rossi said.
Herta had won the Indy 500 in 2011, with Dan Wheldon, using a similar strategy.
After what turned out to be his final pit stop, Rossi managed to squeeze 36 laps out of his tank, while the best anyone else could do in the 200-lap race was 32.
Rossi, who had never finished better than 10th in five previous IndyCar series starts this season, said he had succeeded by being conservative at times, tactical in traffic and resisting the urge to dice with those challenging him for position.
After the veteran Kanaan, the 2013 Indy winner, had to surrender the lead and head to the pit for fuel with seven laps left, the final circuits around the two-and-a-half-mile Indianapolis Motor Speedway racetrack seemed to come down to a shootout between two other young drivers, Munoz and Newgarden. They traded the lead until there were three laps to go, when they joined the mad scramble into the pits among other fuel-starved drivers.
That was when the lead was taken over for good by the dark horse Rossi. In 2005, he had been identified as an up-and-coming prospect after beating 2,000 other drivers in a talent contest sponsored by an energy-drink maker. But he found little opportunity to work as a driver in the United States, so he went to Europe.
While Rossi found his biggest success Sunday by staying out of the pits, that was where the perennial favorites found failure.
The three-time winner Helio Castroneves, who initially could not get his car to fire on the grid, was leading with less than 100 miles to go, but his car also needed a late splash of fuel while running third. He had also escaped damage in one pit road entanglement, but he needed to pit again for a new left rear fender late in the race after being hit from behind by J. R. Hildebrand.
Will Power, another leader, was penalized by being sent to the rear of the field after he collided on pit road with Kanaan. Later, Simon Pagenaud was handed the same penalty when he bumped into Mikhail Aleshin while leaving his pit. The defending Indy 500 champion, Juan Pablo Montoya, a Penske teammate of Castroneves, Power and Pagenaud, escaped injury when he crashed out just after the 150-mile mark.
The chances of the early leaders James Hinchcliffe, the 2014 Indy winner; Ryan Hunter-Reay; and Townsend Bell were dinged by pit road incidents of their own. Hunter-Reay and Bell tangled with Castroneves, who had the right of way and escaped; they, however, ended up sideways and needed repairs. Hinchcliffe lost time for a fuel hose malfunction.
Over all, the raucous, action-packed event seemed like a solid return to form for the famed race and its glorious past. Over the last 20 years, the race and the sport have experienced declining attendance and fan interest. But the huge turnout this year seemed to suggest that the sport’s glory days might be back.
The Indianapolis 500, first run in 1911 but suspended during the two World Wars, enjoyed nearly perfect blue skies for its celebration, with a sellout crowd estimated at more than 400,000. Organizers have said the race attracts the largest single-day attendance of any sports event in the world.
An earlier version of this article misstated Tony Kanaan’s finish. He was fourth, not fifth.